This invention relates to packaging apparatus, and more particularly to apparatus useful in forming pouches to facilitate insertion of articles therein.
Devices are known in the food packaging art for opening thin plastic and/or plastic-foil bags to enable their filling at a station along a transport path of a carrier for such bags. The bags are generally supplied in the form of stacks of flattened bags which may be simple sacks or substantially rectangular plastic panels formed at their bottoms with gussets or a panel of substantially V-cross section so that the section of the bottom has a W-cross section. One system for opening such bags comprises vacuum means for spreading the lips of the mouth of the bag and a mechanical element which is introduced through the open end to spread apart the walls of the bag to the bottom.
Difficulties are frequently encountered with such a system in that the vacuum is often insufficient to maintain the bag in opened position during insertion of the mechanical member at high speed and under high friction generating conditions causing the pouch to fall away from the ram. This has been a particular problem with pouches constructed from materials having high slip properties such as, for example, paraffin-coated or wax treated cellophane.
The following is a listing of U.S. Patents believed material to the state of the art to which this invention pertains.
No. 2,224,656 discloses opposed suction devices movable toward one another to engage a flattened bag and movable apart to open the bag.
No. 2,281,516 discloses opposed suction boxes A for opening collapsed bags B in preparation for filling.
No. 3,453,799 discloses pouch opening apparatus, including suction cups 54, each provided with a flat edge portion 54a for eliminating tendency of the pouch wall to become wrinkled.
No. 4,033,096 discloses opposed pairs of suction cups 6 and 9 operative to engage and spread the walls of flattened pouch 1.
No. 4,150,519 discloses a pair of opposed vacuum boxes that are movable toward and away from one another and comprising vacuum cups having an insert with a recessed face portion whereby a vacuum forces surfaces of a pouch placed between the vacuum boxes onto the vacuum cups and partially into the recessed portion thereof.
It is an object of this invention to provide an improved apparatus of the foregoing type.
It is another object of this invention to provide an improved vacuum apparatus which is particularly adapted to retain thin plastic-foil materials having high slip characteristics to ensure full opening of a pouch through insertion of a mandrel.
These and other objects of the invention will be apparent from the description of the invention which follows.